Silver produced alongside a different primary metal, usually lead, zinc or copper.
Silver recovered as a secondary metal during the processing of ores primarily mined for other metals such as gold, copper, lead, or zinc. Most silver production globally comes from by-product operations rather than primary silver mines.
Most of the world's silver arrives this way, which means silver supply responds to base metal economics rather than to the silver price. It is the main reason silver supply is slow to react to a rally.